Garbage Collection by Ants

Assume there are many tiny pieces of garbage scattered on a 2D square space, where many ants are wandering to forage randomly. Each ant individual behaves according to the following very simple rules when it comes to a place where there is some garbage.

1. If the ant is holding a piece of garbage, it drops it off there.

2. If the ant isn't holding any garbage, it picks up a piece of garbage there.

What would result from these rules? Are the garbage pieces going to be scattered more and more due to these brainless insects? Interestingly, these very simple behavioral rules let the ants spontaneously collect and pile up garbage and clear up the space in the long run. This model tells us how such emergent behavior of the collective is often inconsistent with our usual intuition.

This Demonstration simulates this model using a real-time agent-based modeling technique. Black dots represent ants. Yellow dots represent pieces of garbage. When more pieces of garbage are piled up at the same location, the color becomes darker.